For certain items of everyday use, containers are commercially available which may be connected to each other so to form piles or stacks. In particular, magnetic tape cassette containers are such known to have stacking elements at their upper and lower sides of, e.g., dovetail grooves and ledges or keys, respectively. The dovetailed elements on the upper side of each container are complementary to those on the lower side of the same end of each other container.
It is desirable to stack such containers not only vertically to form a compact block but also to connect them horizontally in juxtaposed position. Designs are known in the state of the art where the individual containers have stacking elements at their upper and lower sides but also at the lateral sides which extend perpendicularly with respect thereto. Reference may be had to U.S. Pat. No. 3,514,170.
This solution appears to be acceptable for relatively large containers where the volume occupied by the stacking elements is small relative to the overall volume of the container. This, however, is not true for the tape cassette containers mentioned above. If lateral stacking elements would be provided at them, the containers would have to be provided with considerably thickened lateral walls which not only means increased volume but also increased material expenses.